


Thy Brother's Blood

by orphan_account



Series: Abel's Blood; Colette's Legacy [1]
Category: Supernatural
Genre: Alternate Universe - Canon Divergence, Angst, Cure for the Mark of Cain (Supernatural), Dean Winchester Bears the Mark of Cain, Demon Dean Winchester, Hurt, M/M, Sam Winchester's Demonic Powers, Season/Series 10
Language: English
Status: In-Progress
Published: 2020-01-07
Updated: 2020-03-11
Packaged: 2021-02-27 05:47:19
Rating: Teen And Up Audiences
Warnings: Major Character Death
Chapters: 3
Words: 2,991
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22162036
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/orphan_account
Summary: Sam isn't the only one waiting to be reunited with his brother. Cain is waiting too. Until one day, he doesn't have to. Meanwhile, Dean has underestimated how much his brother is willing to sacrifice for his sake.
Relationships: Abel/Cain, Cain & Sam Winchester, Cain/Sam Winchester, Dean Winchester/Sam Winchester
Series: Abel's Blood; Colette's Legacy [1]
Series URL: https://archiveofourown.org/series/1595221
Comments: 9
Kudos: 53





	1. The Poison In My Veins

Sam placed the cell phone on top of the car next to the laptop, resisting the urge to throw it on the ground and stomp on it. Crowley hadn't, unfortunately, been stupid enough to keep the conversation going long enough for Sam to trace it. That meant he was back to where he had been: clueless on how to help his brother. 

And that brought him to the next point. Dean was a _demon_? Not that there was a demon stuffed into his meat suit. Dean _was_ a demon. He had _become_ a demon. 

How was that even possible? 

There was no lore on the Mark of Cain. Sam had scoured pretty much every inch of their extensive library. Twice. 

Rage building in his mind, Sam squeezed his eyes shut, trying not to think about what Crowley had said. _Your brother and I, we're BFFs now, as the kids call it... Give up now, moose. Dean chose hell. He chose me. Over you._

No. No, Dean wouldn't do that. Sure, they'd had their differences over the last few months. But demon or not, Sam couldn't fathom Dean leaving him. It just wasn't something that made sense. It was something that Sam had taken for granted. 

Or maybe it was his own fault, Sam thought, desperation mingling with the anger. Sam had forgiven Dean for the Gadreel fiasco. After all, he would have done the same thing, no matter what he'd said. Maybe he should have told Dean that, instead of punishing him for a crime Sam would have committed in a heartbeat. Maybe, if he'd told Dean the real reason he'd been angry, that Dean hadn't trusted Sam enough to tell him the truth later, maybe if he'd stopped being a hypocrite and spoken to his brother that one night Dean had tried to start a conversation, maybe, maybe, maybe, maybe... 

There was the sound of metal hitting metal. 

Sam, realizing he'd buried his face in his hands, started and stared ahead in shock.

The dead demon's cell phone was lying broken at the foot of the nearby wall. The Impala was maybe three feet to the side of where it had been, brushing up against the body of the next car. His laptop, which had been on the hood, had toppled off. 

Sam felt the first sparkings of fear, as he realized what had happened. He could suddenly feel power curling inside him, coming to life and settling in at the top of his spine. Power he hadn't felt in years. This wasn't what he'd had with Ruby. No, that had been ugly, corrupted. _This_ was the power that had prompted him to push a dresser away without his hands, all because he'd been terrified of losing Dean. 

This wasn't demon blood. This was _him_. 

As soon as the fear came, it went. And an idea began to form. An idea so obvious, Sam wanted to kick himself for not thinking of it earlier. It was crazy. It was last-ditch. It probably wouldn't even work. But... 

Nobody would know the Mark of Cain better than the first bearer, right? 

He didn't have time to practice this the proper way. He also was not going to make himself dependent on demon blood. There was only one thing to do: focus on his anger, unhealthy though that was. Given the situation, it wouldn't be difficult. 

Sam took a deep breath. He thought about Dean, thought about Crowley, thought about them together, fighting, fucking, whatever. It was easy- Crowley had painted a vivid picture with very few words. He pictured that damned brand on Dean's arm, about the cursed bone Dean carried as his weapon. Anger rose again and Sam smoothed it over, sharpening it, honing it until it was as deadly as an angel blade. He pictured it as a blade too, imagined wielding it in his hands, like his emotions were something tangible. 

The laptop, thankfully unbroken, gently floated into his hands and the door of the Impala opened like an invitation. 

Sam smiled, knowing he probably looked like a crazy axe murderer. 

He needed to hunt down another demon. And this time, he had a much better way of persuading them to tell him what he wanted to know. 


	2. Little Brothers And Nostalgia

Of all the things that could have happened, the last thing Cain had been expecting was a knock at his door. After the fiasco with the king of hell, the prideful man who'd reminded him too much of himself and the horde of demons he'd arranged to attack them, who could blame him for wanting to return to his peace and quiet? 

But there was a second knock, harder, more insistent, as if the knocker would break down the door if not answered. 

So he opened the door, ready to tell off whoever it was, only to be thrown back against the wall by an unseen force. 

It was more due to shock than anything else that he couldn't block the surge of power that attacked him. He opened his eyes to see his attacker. 

For two agonizingly long seconds, Cain couldn't breathe. All he knew was slanted hazel eyes, pink lips with a perfect cupid's bow and porcelain skin framed by soft shining hair. 

Then as he leaned forward, another burst of power forced him back against the wall. 

"Do you know where my brother is?" The newcomer demanded. 

Cain deliberately relaxed, coming to his senses. He didn't have to ask who this was. Just like his brother, Samuel Winchester was known to everyone in the supernatural world. _Unlike_ his brother, there were some circles in Hell who both revered and feared Samuel. 

"What are you doing in my house?" He asked calmly, as if his long-dead heart wasn't beating frantically, even though, upon closer inspection, Samuel only bore a passing resemblance to Abel. 

"I would think that's pretty obvious," the hunter snarled. 

No, Abel had never looked at Cain with that sort of hatred. Not even when... 

He had to give the boy credit though. Even with one hand wrapped up in a sling, painfully thin and visibly weakened, he didn't seem to have a trace of fear, instead keeping his uninjured arm out, palm extended towards Cain. 

"I don't know where Dean Winchester is," he replied. "How did you find me?"

Samuel smirked. "I have my ways," he answered flippantly. "Now... If you don't know where Dean is, then can you help me find him?"

"No."

"Can't or won't?"

Cain focused. Being a demon for so many centuries had left traces that stayed even after losing the Mark and, with it, his immortality. So, with a little effort, he overcame Samuel's power. The boy wasn't yet strong enough to keep him down.

Samuel looked surprised.

"You're not quite strong enough to keep someone of my strength pinned," Cain told him, then turned towards the kitchen. "As to your question, the answer is simple. Both. If you can't find your brother, you who knows him best, then I don't stand much chance. And even if I could, why should I?"

There was silence. Frowning, Cain looked back. 

Samuel was swaying lightly on the spot, eyes downcast, face set in bitterness. And once again, Cain couldn't see the Morningstar's vessel anymore. All he could see was a little brother, a boy who wanted his elder brother to hold him. 

Cain almost moved to him, a long-dormant instinct taking over. He resisted. 

"Tell me what happened," he suggested, sitting on the arm chair. "Perhaps... Perhaps I can offer advice."  


scowled. "Oh, now you're interested?" He scoffed. "Dean told me getting your attention was like pulling teeth."

"True." Cain shrugged. "But his visit had awoken some desire for company." He didn't mention that he was sure Samuel would only run off to hunt his brother once again and Cain couldn't let him do that in the condition he was in. He wasn't sure how long the boy had been alone, or how he'd survived in his condition, but he wouldn't for much longer.

Samuel seemed to come to some sort of decision. He gingerly sat at the very edge of the sofa. "Are you going to have a horde of demons attack me?" He asked, only half serious. 

Cain shook his head. "As I said, I am weary of loneliness. And you would handle them effortlessly anyhow. So talk."

And talk Samuel did. He made a valiant effort to keep his voice level as he spoke about Dean's death, his disappearance and the subsequent search. But when he got to the last part, his mask cracked, ever so slightly. 

"The King of Hell informed me," he murmured. "Dean... He's not Dean anymore. He's a demon. A Knight of Hell."

Cain had known this the second Samuel had mentioned the death. 

"The Mark does not stop tormenting it's bearer until it's appetite is satisfied. Not even death is an obstacle. It is easiest to change a soul when the body and mind is dead. The Mark revived him in a way that would ensure a steady diet."

"A diet of blood," Samuel muttered. "Is there any way to fix him?"

"Not that I'm aware of," Cain lied. He surprised himself. He already had a theory, unproven though it was. But he wanted to keep this man here, for at least a little while longer. There was no point in lying to himself about why. But that didn't change how bad an idea it was. He was already too concerned about Samuel's health. 

Samuel sighed. "Is there any way you can help me?" He asked, not even trying to hide his desperation. Cain saw his fingers twitch. If Samuel suspected him of lying, he'd resort to his powers. And hurt himself doing so. 

But Cain had been lying for longer than Samuel had lived, even counting the five thousand years spent in the Cage. 

"I have a rather extensive library," he said quietly. "With books you won't find anywhere else in the world. Stay here for some time. Perhaps a fresh pair of eyes will help. You might find something I didn't."

When Samuel looked wary, he appealed to logic as well. "In any case, it would do you good to rest. Even with your powers, you are in no condition to take on a Knight of Hell."

The suspicion didn't dissipate. "Why are you helping me?" He asked, voice low and dangerous. 

Cain got to his feet. Before leaving to put on tea, he thought of the best way to answer. This wasn't something he wanted to lie about. "I hadn't thought about my brother willingly before I gave up the Mark. Now, free of that influence, there are times when he is all I can think of." He paused, watching Samuel's face, basking in the sensation of Abel's bloodline. Then he said quietly, "You have his eyes."


	3. By His Own Words

"Holy crap," Sam mumbled weakly. The library lay below a trapdoor, in what might as well be a nuclear bunker under the cabin. The shelves of books were at least as extensive as the MoL archives in the bunker. "And this is all pre-biblical?" He asked. 

"Nearly all of it," Cain assured. 

Sam sneaked a glance at him. Cain stood still, but there was an energy about him, simmering under his skin, that reminded him too much of Dean. Sam could almost feel the nervousness emanating from the former Knight, nervousness that he tried, and almost succeeded, to hide. 

But Sam's psychic powers had, in fact, worked like ' _flipping a switch_.' He couldn't yet hear thoughts, but he could sense the underlaying emotions. 

"And, in all your eons spent here, you've never found a single thing that could help?" Call him paranoid, but Sam had no reason to trust this man with anything. Except right now, he didn't seem to have much choice. Cain was too ancient and too powerful for Sam to take on just yet. 

"No," was the blunt answer he got. 

"Okay, then," Sam replied, slowly. "Let's get reading. Where should we start?"

Cain strode ahead and picked out two books bound in cracked leather. "I should replace the covers soon," he muttered. He turned to Sam. "How fluent are you in Hebrew?"

"Very fluent," he replied. 

Cain handed him the black one first. "That is Abel's diary. Once you're done with that..." He handed over the brown one. "This is mine. I haven't read either in years." He started walking back towards the stairs. "I'm going to cook dinner. You start reading."

"I'm sorry, you're going to cook?" Sam asked, raising an eyebrow. 

Cain didn't grace him with a look. "How do you think I eat?"

Sam sighed, as he disappeared, and looked at the books in his hands. Taking a seat at the small table and single chair, he opened Abel's diary. 

Most of it was inane. Stuff about their daily rituals, their parents, Eve's lament for falling for the snake's trick, Adam's ready forgiveness for her mistake, herding the sheep, looking after the crops. Normal. Peaceful. 

The only thing that stood out? It was when the brothers seemed to have reached adulthood. 

_It has taken me years to realize, or perhaps I always knew and am only now acknowledging it, that Cain is my one true constant on God's earth. For all our childhood adventures into the forests and the long hours spent together watching the stars dance across the sky, he is the most beautiful thing I have ever known._

_Our parents had said they are each other's soulmates, two halves made whole, created from the same source._

_There is no doubt in my mind that my brother and I are similar. He is my other half. He is my partner. And he is my lover. As I am his._

_I know he worries for me. He worries that my dreams are a thing of trickery and deceit, not a message from the Father. He is jaded, perhaps, after mother's departure. When she disappeared with no clue as to her whereabouts, our father was heartbroken and distant, and Cain became hardened and guarded. Perhaps, he fears that I too shall disappear. I can only hope, with time, to convince him that I cannot fathom a life away from him. I choose to spend all my days by his side and I shall rather be damned than breath my last anywhere except in his arms._

Sam closed the book, unable to read any further. He buried his head in his hands. The parallels hurt. Abel had spoken with Lucifer, thinking he was God. Sam had thought he was speaking to Jessica when the Morningstar had first appeared to him. Eve had disappeared, presumably to Purgatory, for unknown reasons, and Mary had died. Both had left their respective husbands in despair and their eldest sons to pick up the slack. Both Cain and Dean had dedicated their lives to their younger brothers and both had been terrified of being left behind. 

Except, Sam thought bitterly, Abel had obviously been a much better brother than him. Simply, because he'd never walked away from Cain, while Sam could count the number of times he'd left Dean. 

And the other difference... Cain and Abel had been lovers. Between him and Dean, they'd religiously ignored the tension between them, the feeling of comforting hands on skin while patching up wounds, the warmth of shared breath when they got too close while sparring... All of it. They'd just pretended it didn't exist, unwilling to cross that final line. And for what? Societal rules? The law? Morality? 

As if they hadn't already broken laws and taboos before. As if their Jiminy Crickets weren't weather vanes at the best of times. 

Cain's voice echoed down into the vast space. "Dinner is ready, if you have finished the diary."

Sam stared at the other diary- Cain's diary. Then he tucked it into his jacket and made his way up to the main part of the house. 

Cain had set the table for two. There wasn't any electricity in the house- the running water must be magic- so, there were candles and oil lamps set around the room, also magical probably, based on the unnatural brightness. It gave the whole space an intimate feel and Sam wanted to fidget when he realized it. 

As he made his way to the table, he spotted a single photograph on the mantel. It was of a woman, maybe in her thirties. The photo was old, but Sam could make out thick black hair, mischievous eyes that would make any guy go a little crazy, and a smile that radiated kindness. 

"Is that Colette?" He asked, recalling what Dean had told him.   
"Yes." Cain, surprisingly, looked like it hurt him to remember her. Or maybe not surprisingly, considering what she had been to him. 

"What was she like?" Sam asked, gently, taking a bite of whatever was on his plate. He didn't care for the specifics just now; it was vegetables and that was good enough for him. 

Cain had a far away look in his eye. "Kind. Sweet. Docile, but with a secret fire. Hardly timid, but shy. A bundle of contradictions." The last part was said with a smile and Sam felt himself do a double take at how it transformed Cain's face completely, making him look less hermit-like and more... Handsome.

It was a disconcerting thought, considering the only man Sam had ever thought of that way was, well, his own brother. 

_No_ , he told himself firmly. It was just the words from Abel's diary imprinting in his mind. It would not do at all to catch even a hint of feelings of any kind whatsoever for the Father Of Murder. 

But then Cain was looking at him again, with that same wonder-struck, _I-can't-believe-you're-here_ expression that Dean wore sometimes, and it sparked a warm feeling somewhere in his chest. 

_Fuck_.   
  



End file.
